The total amount of data on skeletal muscle metabolism published during the last 15 years contrasts with the paucity of information on smooth muscle metabolism over this same period. During the past few years, we have studied the intermediary metabolism of subhuman primate myometrium using myometrial slices and cell-free extracts and by measuring in situ levels of the constituents and co-factors of the glycolytic pathway. The overall purpose of our studies is to gain information on the metabolic control mechanisms and the interrelations of carbohydrate, lipid, and protein metabolism of myometrium and how prostaglandins and prostoglandin inhibitors such as indomethacin affect these pathways. The effect of prostaglandins and indomethacin on the ratio of cyclic AMP to cyclic GMP in myometrium from pregnant rhesus monkeys and in myometrium during the intermenstrual period will be determined. Since the cyclic AMP level is closely linked to the control of such rate-limiting enzymes as phosphofructokinase, we plan to identify and study the regulatory enzymes in myometrial glycolysis. Several approaches will include: 1) mass-action ratios in situ and in vitro under different physiological conditions; 2) the effects of an altered flux rate in vitro on the intracellular levels of relevant metabolic intermediates and co-factors; 3) the rates of product formation from labeled precursors such as glucose, glucose-6-PO4, and fructose-6-PO4 by cell-free myometrial extracts and purified enzymes. We will also investigate the effect of prostaglandins and indomethacin on the kinetics of the enzymes that synthesize and degrade cAMP in pregnant myometrium and in myometrium during the intermenstrual period. The tissue levels of cyclic nucleotides may be important in the regulation of smooth muscle contractility and tone. In view of the possible clinical use of PGs and indomethacin to affect uterine motility, we plan to study the ratio of cAMP to cGMP in myometrium during spontaneous and induced uterine contractions. We will collect biopsies of resting and contracting myometrium during the first hours after parturition. We also have available a modified Warburg flask that holds the muscle at a fixed length; contractures can be induced electrically through electrode wires embedded in the holder or chemically by tipping in substances from a side arm.